Prosthetic heart valve having improved commissure supports

ABSTRACT

A method of implanting a prosthetic heart valve within a patient can comprise inserting a distal end portion of a delivery apparatus and a prosthetic heart valve into the patient and advancing the prosthetic heart valve to a deployment location within the heart of the patient and inflating one or more of a plurality of differently-sized balloons in a balloon-assembly on the distal end portion of the delivery apparatus. The prosthetic heart valve can be mounted on the balloon assembly in a crimped state and the inflating of the one or more of the plurality of differently-sized balloons can expand the prosthetic heart valve from the crimped state to a radially expanded state having a non-cylindrical shape.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/525,439, filed Jul. 29, 2019, which is a continuation of U.S.application Ser. No. 15/697,740, filed Sep. 7, 2017 and issued as U.S.Pat. No. 10,363,132, which is a continuation of U.S. application Ser.No. 14/922,057, filed Oct. 23, 2015 and issued as U.S. Pat. No.9,757,229, which is a continuation of U.S. application Ser. No.13/708,598, filed Dec. 7, 2012 and issued as U.S. Pat. No. 9,168,131,which claims the benefit of U.S. Provisional Application No. 61/569,022,filed Dec. 9, 2011, each of which are incorporated by reference hereinin their entirety.

FIELD

The present disclosure concerns embodiments of a prosthetic heart valve,and delivery systems for implanting prosthetic heart valves.

BACKGROUND

The human heart can suffer from various valvular diseases. Thesevalvular diseases can result in significant malfunctioning of the heartand ultimately require replacement of the native valve with anartificial valve. There are a number of known artificial valves and anumber of known methods of implanting these artificial valves in humans.

Various surgical techniques may be used to replace or repair a diseasedor damaged native valve. Due to stenosis and other heart valve diseases,thousands of patients undergo surgery each year wherein the defectivenative heart valve is replaced by a prosthetic valve. Another lessdrastic method for treating defective valves is through repair orreconstruction, which is typically used on minimally calcified valves.The problem with surgical therapy is the significant risk it imposes onthese chronically ill patients with high morbidity and mortality ratesassociated with surgical repair.

When the native valve is replaced, surgical implantation of theprosthetic valve typically requires an open-chest surgery during whichthe heart is stopped and patient placed on cardiopulmonary bypass (aso-called “heart-lung machine”). In one common surgical procedure, thediseased native valve leaflets are excised and a prosthetic valve issutured to the surrounding tissue at the native valve annulus. Becauseof the trauma associated with the procedure and the attendant durationof extracorporeal blood circulation, some patients do not survive thesurgical procedure or die shortly thereafter. It is well known that therisk to the patient increases with the amount of time required onextracorporeal circulation. Due to these risks, a substantial number ofpatients with defective native valves are deemed inoperable becausetheir condition is too frail to withstand the procedure. By someestimates, more than 50% of the subjects suffering from valve stenosiswho are older than 80 years cannot be operated on for valve replacement.

Because of the drawbacks associated with conventional open-heartsurgery, percutaneous and minimally-invasive surgical approaches aregarnering intense attention. In one technique, a prosthetic valve isconfigured to be implanted in a much less invasive procedure by way ofcatheterization. For instance, U.S. Pat. Nos. 5,411,522 and 6,730,118,which are incorporated herein by reference, describe collapsibletranscatheter prosthetic heart valves that can be percutaneouslyintroduced in a compressed state on a catheter and expanded in thedesired position by balloon inflation or by utilization of aself-expanding frame or stent.

An important design parameter of a transcatheter prosthetic heart valveis the diameter of the folded or crimped profile. The diameter of thecrimped profile is important because it directly influences thephysician's ability to advance the transcatheter prosthetic heart valvethrough the femoral artery or vein. More particularly, a smaller profileallows for treatment of a wider population of patients, with enhancedsafety.

SUMMARY

The present disclosure is directed to embodiments of catheter-basedprosthetic heart valves. A prosthetic heart valve according to thepresent disclosure comprises a radially collapsible and expandableannular frame and a leaflet structure comprising a plurality of leafletsmounted within the frame. The frame in particular embodiments can havecommissure attachment portions that are configured to support thecommissures of the leaflets at locations spaced radially inwardly towardthe longitudinal flow axis of the prosthetic valve relative to the frameportions circumscribing the moveable portions of the leaflets. When theleaflets open under pressure of blood flowing through the prostheticvalve, the moveable portions of the leaflets are retained at positionsspaced inwardly from the inner surface of the frame to protect againstabrasion of the leaflets.

In one representative embodiment, a prosthetic valve comprises aradially collapsible and expandable annular frame. The frame has aplurality of angularly spaced commissure attachment portions and aplurality of lobed portions extending between the commissure attachmentportions. The frame also has an inlet end and an outlet end. A leafletstructure comprises a plurality of leaflets, each leaflet comprisingopposing side portions and an upper edge extending between the sideportions. Each side portion is secured to an adjacent side portion ofanother leaflet to form commissures of the leaflet structure, eachcommissure being attached to one of the commissure attachment portionsof the frame. The leaflets are configured to move between an openposition to allow blood to flow through the prosthetic valve from theinlet end to the outlet end and a closed position to inhibit the flow ofblood through the prosthetic valve from the outlet end to the inlet end,wherein the upper edges of the leaflets are spaced radially inwardly ofthe lobed portion of the frame when the leaflets are in the openposition.

In another representative embodiment, a prosthetic valve comprises aradially collapsible and expandable annular frame. The frame comprisesan inlet portion and an outlet portion, the outlet portion comprising aplurality of angularly spaced, cantilevered commissure attachment postsextending radially inwardly toward a longitudinal flow axis of theprosthetic valve. A leaflet structure comprises a plurality of leaflets,each leaflet comprising opposing side portions, a scalloped upper edgeextending between the side portions, and a scalloped lower edgeextending between the side portions. Each side portion is secured to anadjacent side portion of another leaflet to form commissures of theleaflet structure, each commissure being attached to one of thecommissure attachment posts. The leaflets are configured to move betweenan open position to allow blood to flow through the prosthetic valvefrom the inlet portion to the outlet portion and a closed position toinhibit the flow of blood through the prosthetic valve from the outletportion to the inlet portion, wherein the upper edges of the leafletsare spaced radially inwardly of the frame when the leaflets are in theopen position such that a gap is formed between the upper edge of eachleaflet and the frame.

In another representative embodiment, a prosthetic valve comprises aradially collapsible and expandable annular frame. The frame has aplurality of angularly spaced commissure attachment posts, eachcommissure attachment post comprising at least two cantilevered strutsspaced apart from each other to define a leaflet-receiving gap. Aleaflet structure comprises a plurality of leaflets, each leafletcomprising opposing side portions and an upper edge extending betweenthe side portions. Each side portion is secured to an adjacent sideportion of another leaflet to form commissures of the leaflet structure.Each commissure extends through the leaflet-receiving gap of arespective commissure attachment post, and the struts of the commissureattachment post are compressed toward each to clamp the commissurebetween the struts.

In another representative embodiment, a prosthetic valve comprises aradially collapsible and expandable annular frame that is plasticallyexpandable. The frame comprises a plurality of angularly spacedcommissure attachment posts. A leaflet structure comprises a pluralityof leaflets, each leaflet comprising opposing side portions, whereineach side portion is secured to an adjacent side portion of anotherleaflet to form commissures of the leaflet structure, each commissurebeing attached to one of the commissure attachment posts. The commissureattachment posts are configured to deflect radially inwardly toward alongitudinal flow axis of the prosthetic valve when first subjected toclosing forces of the leaflets immediately following implantation of theprosthetic valve and then remain in the deflected position duringsubsequent closing and opening cycles of the prosthetic valve.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prosthetic heart valve, according toone embodiment.

FIG. 2 is a top plan view of the prosthetic heart valve of FIG. 1,showing the leaflets in the open position.

FIG. 3 is a top plan view of the prosthetic heart valve of FIG. 1,showing the leaflets in the closed position.

FIG. 4 is a flattened view of the frame of the prosthetic heart valve ofFIG. 1, as laser cut from a tubular member.

FIG. 5 is a perspective view of the frame of FIG. 4, as laser cut from atubular member.

FIG. 6 shows a leaflet of the prosthetic heart valve of FIG. 1, shown ontop of a known leaflet for purposes of comparison.

FIG. 7 is a perspective view of a prosthetic heart valve, according toanother embodiment.

FIG. 8 shows a flattened view of a skirt for a prosthetic heart valve,according to one embodiment.

FIGS. 9 and 10 show two positions for implanting a prosthetic heartvalve in the aortic annulus.

FIG. 11 is a side view of a balloon assembly of a delivery apparatus,according to one embodiment, that can be used for implanting aprosthetic heart valve.

FIG. 12 is a top plan view of the balloon assembly of FIG. 11.

FIG. 13 is a side elevation of a prosthetic heart valve, according toanother embodiment.

FIG. 14 is a top plan view of the prosthetic valve shown in FIG. 13,showing the leaflets in the closed position.

FIG. 15 is a flattened view of the frame of the prosthetic valve shownin FIG. 13.

FIG. 15A is an enlarged view of a portion of the frame shown in FIG. 15.

FIG. 16 is a top plan view of the prosthetic valve of FIG. 13, showingthe leaflets in the open position.

FIG. 17 is a perspective view of a leaflet and a portion of the frame ofthe prosthetic valve of FIG. 13, showing the commissure of the leafletsupported at angle of about 60 degrees relative to the longitudinal flowaxis of the valve.

FIG. 18 is a perspective view similar to FIG. 17, showing the commissureof the leaflet supported at an angle of about 15 degrees relative to thelongitudinal flow axis of the prosthetic valve.

FIG. 19 is a flattened view of a leaflet of the prosthetic valve of FIG.13.

FIGS. 20-25 are various views illustrating the connection of acommissure to the frame of the prosthetic valve of FIG. 13.

FIG. 26 is a flattened view of another embodiment of a frame that can beused in the prosthetic valve of FIG. 13.

FIG. 27 is a perspective view of a prosthetic heart valve, according toanother embodiment.

FIG. 28 is an enlarged view of a section of the prosthetic valve of FIG.27, showing the connection of a commissure to the frame of the valve.

FIG. 29 is a perspective view of another embodiment of a frame that canbe used in the prosthetic valve of FIG. 27, showing the frame in anexpanded state immediately after deployment by a balloon.

FIG. 30 is a perspective view of the frame of FIG. 29, showing the frameafter the commissure posts are displaced by the closing forces of theleaflets.

FIG. 31 is a side elevation view of the frame of FIG. 30.

FIG. 32 is a cross-sectional view of the frame of FIG. 31.

FIG. 33 is an enlarged view of a weakened portion of the commissure postof the frame shown in FIG. 32.

FIG. 34 is a perspective view of an alternative embodiment of the frameshown in FIG.

29.

DETAILED DESCRIPTION

The present disclosure is directed to embodiments of catheter-basedprosthetic heart valves. Several exemplary embodiments of prostheticheart valves are disclosed herein and shown in the attached figures.These embodiments should not be construed as limiting in any way.Instead, the present disclosure is directed toward all novel andnonobvious features and aspects of the various disclosed embodiments,alone and in various combinations and sub-combinations with one another.

FIG. 1 is a perspective view of a prosthetic heart valve 10, accordingto one embodiment. The illustrated prosthetic valve is adapted to beimplanted in the native aortic annulus, although in other embodiments itcan be adapted to be implanted in the other native annuluses of theheart. The prosthetic valve 10 can have three main components: a stent,or frame, 12, a valvular structure 14, and an inner skirt 16. Theprosthetic valve 10 is configured to be radially compressed to a crimpedstate for delivery into the body of a patient and radially expandablefrom the crimped state to an expanded state once positioned at thedesired implantation location within the body.

The valvular structure 14 can comprise three leaflets 40, collectivelyforming a leaflet structure, which can be arranged to collapse in atricuspid arrangement, as best shown in FIG. 3. The leaflets 40 can beformed of pericardial tissue (e.g., bovine pericardial tissue),biocompatible synthetic materials, or various other suitable natural orsynthetic materials as known in the art and described in U.S. Pat. No.6,730,118, which is incorporated by reference herein.

FIG. 4 shows a flattened view of the bare frame 12 and FIG. 5 shows aperspective view of the bare frame as laser cut from a tubular member,prior to any shape forming. The frame 12 can be formed with a pluralityof circumferentially spaced commissure supports 18 (three in theillustrated embodiment), each of which comprises two axial struts 34defining a respective slot, or commissure window, 20 therebetween thatis adapted to mount the commissures of the valvular structure 14 to theframe, as described in greater detail below. The frame 12 can be made ofany of various suitable plastically-expandable materials (e.g.,stainless steel, etc.) or self-expanding materials (e.g., Nitinol) asknown in the art. When constructed of a plastically-expandable material,the frame 12 (and thus the prosthetic valve 10) can be crimped to aradially compressed state on a delivery catheter and then expandedinside a patient by an inflatable balloon or equivalent expansionmechanism. When constructed of a self-expandable material, the frame 12(and thus the prosthetic valve 10) can be crimped to a radiallycompressed state and restrained in the compressed state by insertioninto a sheath or equivalent mechanism of a delivery catheter. Onceinside the body, the prosthetic valve can be advanced from the deliverysheath, which allows the prosthetic valve to expand to its functionalsize.

Suitable plastically-expandable materials that can be used to form theframe 12 include, without limitation, stainless steel, a nickel basedalloy (e.g., a cobalt-chromium or a nickel-cobalt-chromium alloy),polymers, or combinations thereof. In particular embodiments, frame 12is made of a nickel-cobalt-chromium-molybdenum alloy, such as MP35N™(tradename of SPS Technologies), which is equivalent to UNS R30035(covered by ASTM F562-02). MP35N™/UNS R30035 comprises 35% nickel, 35%cobalt, 20% chromium, and 10% molybdenum, by weight. It has been foundthat the use of MP35N to form frame 12 provides superior structuralresults over stainless steel. In particular, when MP35N is used as theframe material, less material is needed to achieve the same or betterperformance in radial and crush force resistance, fatigue resistances,and corrosion resistance. Moreover, since less material is required, thecrimped profile of the frame can be reduced, thereby providing a lowerprofile prosthetic valve assembly for percutaneous delivery to thetreatment location in the body.

The frame 12 can also include a plurality of axially extending posts 22extending from the outflow end of the frame. The posts 22 are used toform a releasable connection between the prosthetic valve 10 andcorresponding components at the distal end of a delivery catheter toretain the prosthetic valve at the end of the delivery catheter untilthe prosthetic valve is properly positioned at its target deploymentlocation within the body. The posts 22 typically are used when the frameis a self-expanding frame since there is no balloon to retain theprosthetic valve in place during deployment. If the frame is aplastically-expandable frame that is deployed with a balloon or similarexpansion device, the posts 22 typically are not provided. Details of adelivery device that is configured to retain a self-expandableprosthetic valve via posts 22 is disclosed in U.S. Patent ApplicationPublication No. 2010/0049313, which is incorporated herein by reference.

Referring to FIG. 1, the frame 12 includes an inflow end 24, an outflowend 26, a lower portion 28 and an upper portion 30. As best shown inFIGS. 2 and 3, the upper portion 30 has a tri-lobed cross-sectionalshape in a plane perpendicular to the longitudinal axis A of theprosthetic valve at least when the frame is in it expanded state. Theupper portion 30 defines three lobed-shaped portions 32 that mimic theshape of the sinuses of the aortic root. The lower portion 28 of theframe desirably has a generally conical or flared shape that tapers fromthe inflow end 24 toward the upper portion 30 to assist in anchoring theprosthetic valve to the native annulus once implanted. In otherembodiments, the lower portion 28 of the frame can have an overallcylindrical shape from the inflow end 24 to the lower end of the upperportion 30. If the frame 12 is constructed of a self-expandable material(e.g., Nitinol), then the frame can be shape set to assume the shapeshown in FIGS. 1-3 when the frame radially expands to its expandedstate. If the frame 12 is constructed of a plastically-expandablematerial, then a specially designed delivery device can be used to causethe frame to expand to the shape shown in FIGS. 1-3. One such deliverydevice is shown in FIGS. 9-11 and described below.

The leaflet assembly 14 defines three commissures 42 where the adjacentsides of the leaflets 40 are secured to each other. The commissures 42desirably are secured to the upper portion 30 of the frame 12 atlocations closest to the longitudinal axis A of the prosthetic valve(which correspond to the locations around the frame where the adjacentends of the lobed portions 32 meet). The frame 12 can be provided withcommissure window frame portions 18 at these locations of the frame tofacilitate attachment of the commissures 42 to the frame. Eachcommissure 42 can be formed by securing each leaflet tab 44 (FIG. 6)with an adjacent tab 44 of another leaflet 40. The commissures 42 can besecured to the frame by inserting each pair of leaflet tabs 44 through arespective slot 20 in a frame portion 18, and securing the leaflet tabs44 to the axial struts 34, such as with sutures. Further detailsregarding various techniques for securing the commissures to the windowframe portions 18 are disclosed in co-pending U.S. application Ser. No.13/253,689, filed Oct. 5, 2011, which is incorporated herein byreference.

FIG. 6 shows a leaflet 40 superimposed over a known leaflet 150 for thesame size prosthetic valve. As shown, the leaflet 40 in the illustratedembodiment includes a substantially V-shaped lower edge extendingbetween the lower edges of the tabs 44 and a gently curved, orscalloped, upper edge 48 extend between the upper edges of the tabs 44.Because the commissures 42 are secured to the frame 12 at locationsspaced radially inwardly toward the longitudinal center axis A relativeto the radially outermost sections of the lobed portions 32, the width Wof the leaflet (measured between opposing side edges at any locationalong the height H of the leaflet) can be much less than the width ofthe leaflet 150. Similarly, the opposing sides of the lower edge 46 canhave a greater taper (i.e., the width of the lower portion of theleaflet decreases at a greater rate from top to bottom) than the leaflet150. Consequently, the leaflets 40 are much smaller than typicalconventional leaflets for the same size prosthetic valve, and thereforeoccupy much less space inside the prosthetic valve. As a result, theprosthetic valve 10 can be crimped to a smaller diameter for delivery.

An important design criterion of a prosthetic heart valve is to preventor minimize contact between the movable portions of the leaflets and theinner surface of the frame. Repeated contact between the movableportions of the leaflets and the metal frame during operation of theprosthetic valve can cause premature wear and eventual failure of theleaflets. To mount a leaflet assembly to a frame having a cylindricalcross section, it is known, for example, to use additional metal strutsor bars or additional layers of material to mount the commissures atlocations spaced radially inward from the inner surface of the frame,which assists in preventing contact between the leaflets and the frame.Unfortunately, the use of additional components or additional layers ofmaterial for the mounting the commissures takes up valuable space insideof the frame and can limit the overall crimping profile of theprosthetic valve.

To address these concerns, the upper portion 30 of the frame 12 isshaped such that the commissure support portions of the frame are spacedradially inwardly toward the center axis A of the prosthetic valverelative to the adjacent sections of the frame, without using anyadditional components or layers of material inside the frame to offsetthe commissures from the inner surface of the frame. As noted above, thecommissures 42 of the leaflets are supported at locations where the endsof the lobed portions 32 meet or converge. As a result, contact betweenthe leaflets 40 and the inner surface of the lobed portions 32 can beavoided during operation of the prosthetic valve. As best shown in FIG.2, the upper free edges 48 of the leaflets are spaced inwardly from thelobed portions 32 by a distance G when the leaflets are open undersystolic pressure. Advantageously, since the shape of the frame itselfsupports the commissures 42 radially inward of the frame sectionsbetween the commissure supports 18 without additional components insideof the prosthetic valve, the prosthetic valve 10 can be crimped to asmaller diameter for delivery.

Also due to the shape of the frame, during operation of the prostheticvalve, the commissure supports 18 of the frame can flex slightlyradially inwardly and outwardly to reduce stress on the commissureattachment points (the locations were the leaflet tabs 44 are sutured tothe frame). As noted above, the leaflets 40 can have a scalloped orcurved upper edge 48. As a result, the coaptation lines of the leafletsduring diastole are lowered, creating a force vector acting downwardly(axially) from the commissures, which reduces stress on the commissureattachment points.

The prosthetic valve 10 desirably is implanted within a native annulus(e.g., the aortic annulus) such that the lower portion 28 of the frameserves as an anchor to retain the prosthetic valve against the nativeanatomy. Most of the upper portion 30 of the frame is positioned abovethe native annulus and has sufficient flexibility to attain the desiredsize and shape when expanded regardless of the shape of the nativeannulus. For example, in the case of an oval native annulus, the upperportion 30 of the frame can bend or flex relative to the lower portion28 in order to expand to its desired functional size and shape to ensureproper operation of the prosthetic valve. In the case of a relativelysmall native annulus, which can prevent full deployment of the lowerportion 28, the upper portion can fully expand to its desired functionalsize and shape to ensure proper operation of the prosthetic valve.

The frame also is less sensitive to under deployment of the upperportion of the frame. Because the commissures of the leaflets are spacedradially inward from the lobed portions, a radial force applied to theupper portion will first compress the lobed portions in the radialdirection before the commissures start to move inwardly. That is, thedistance between the commissures 42 stays substantially constant as thelobed portions 32 are radially compressed a predetermined amount. In oneimplementation, the distance between the commissures 42 stayssubstantially constant when the diameter of the outflow end of theprosthetic valve is reduced by about 2.5 mm. Thus, if the upper portionof the frame is slightly under expanded due to the positioning of theprosthetic valve and/or the shape of the native annulus, the commissures42 can still achieve their functional size, which promotes optimumleaflet performance and increased durability of the leaflets. Similarly,because leaflet function is not effected by a certain degree of underexpansion of the frame, a prosthetic valve of a certain size can beimplanted in a greater range of annulus sizes. Thus, the number ofprosthetic valve sizes for treating a wide range of patients can bereduced.

The spaces between the skirt 16 and the outer surfaces of the leaflets40 within the lobed portions 32 of the frame create artificial sinusesthat are shaped similar to and mimic the Valsalva sinuses. Thus, whenthe leaflets close, backflow entering these artificial sinuses create aturbulent flow of blood along the upper surfaces of the leaflets. Thisturbulence assists in washing the leaflets and the skirt to minimizeclot formation.

The commissures 42 can also be secured to a frame that does not have anywindow frame portions 18. FIG. 7, for example, shows a prosthetic valve100, according to another embodiment. The prosthetic valve 100 comprisesa frame 102, a valvular structure 14 mounted to the frame 102, and askirt 16. Like the frame 12 described above, the frame 102 has agenerally conical or flared lower portion 104 and a tri-lobed shapedupper portion 106 and functions in the manner described above. The frame102 comprises a mesh like structure defining a plurality of openings orcells formed by the struts of the frame. The frame 102 has asubstantially homogeneous or uniform structure in that the size andshape of all of the openings are substantially the same. The leafletstabs 44 can be sutured to the struts of the frame 102 adjacent theoutflow end and the lower edges 46 of the leaflets 40 (not shown in FIG.7) can be sutured to the skirt 16 with sutures, as described above inconnection with prosthetic valve 10. The frame 102 can also includeposts 22 (not shown in FIG. 7) for connection to a delivery apparatus.

The main functions of the skirt 16 are to assist in securing thevalvular structure 14 to the frame 12 and to assist in forming a goodseal between the prosthetic valve and the native annulus by blocking theflow of blood through the open cells of the frame 12 below the loweredge of the leaflets. The skirt 16 desirably comprises a tough, tearresistant material such as polyethylene terephthalate (PET), althoughvarious other synthetic or natural materials can be used. The thicknessof the skirt desirably is less than 6 mil, and desirably less than 4mil, and even more desirably about 2 mil. In particular embodiments, theskirt 16 can have a variable thickness, for example, the skirt can bethicker at its edges than at its center. In one implementation, theskirt 16 can comprise a PET skirt having a thickness of about 0.07 mm atits edges and about 0.06 mm at its center. The thinner skirt can providefor better crimping performances while still providing good perivalvularsealing.

As shown in FIG. 1, the skirt 16 can be secured to the inside of frame12 via sutures 60. Valvular structure 14 can be attached to the skirtvia one or more thin PET reinforcing strips (not shown) placed along thelower edges 48 of the leaflets, which enable a secure suturing andprotects the pericardial tissue of the leaflet structure from tears.Valvular structure 14 can be sandwiched between skirt 16 and the thinPET strips. Sutures can be used to secure the PET strips and the leafletstructure 14 to the skirt 16 along a suture line 62 that tracks thecurvature of the bottom edges 48 of the leaflets.

Referring to FIG. 8, in contrast to known fabric skirts, the skirt 16desirably is woven from a first set of fibers, or yarns or strands, 78and a second set of fibers, or yarns or strands, 80, both of which arenon-perpendicular to the upper edge 82 and the lower edge 84 of theskirt. In particular embodiments, the first set of fibers 78 and thesecond set of fibers 80 extend at angles of about 45 degrees relative tothe upper and lower edges 82, 84. The skirt 16 can be formed by weavingthe fibers at 45 degree angles relative to the upper and lower edges ofthe fabric. Alternatively, the skirt can be diagonally cut from avertically woven fabric (where the fibers extend perpendicular to theedges of the material) such that the fibers extend at 45 degree anglesrelative to the cut upper and lower edges of the skirt. As further shownin FIG. 8, the opposing short edges 86, 88 of the skirt desirably arenon-perpendicular to the upper and lower edges 82, 84. For example, theshort edges 86, 88 desirably extend at angles of about 45 degreesrelative to the upper and lower edges and therefore are aligned with thefirst set of fibers 78. Therefore the overall shape of the skirt is thatof a rhomboid.

The upper edge portion of the skirt 16 can be formed with a plurality ofprojections 96 that define an undulated shape that generally follows theshape of the row of struts below the commissure portions 18. In thismanner, the upper edge of skirt 16 can be tightly secured to the strutswith sutures 60. Skirt 16 can also be formed with slits 98 to facilitateattachment of the skirt to the frame. Slits 98 are dimensioned so as toallow an upper edge portion of skirt to be partially wrapped around thestruts and reduce stresses in the skirt during the attachment procedure.For example, skirt 16 is placed on the inside of frame 12 and an upperedge portion of the skirt can be wrapped around the upper surfaces ofthe struts and secured in place with sutures 60. Wrapping the upper edgeportion of the skirt around the struts in this manner provides for astronger and more durable attachment of the skirt to the frame.

Due to the orientation of the fibers relative to the upper and loweredges, the skirt can undergo greater elongation in the axial direction(i.e., in a direction from the upper edge 82 to the lower edge 84).Thus, when the metal frame 12 is crimped, the skirt 16 can elongate inthe axial direction along with the frame and therefore provides a moreuniform and predictable crimping profile. Each cell of the metal framein the illustrated embodiment includes at least four angled struts thatrotate towards the axial direction (i.e., the angled struts become morealigned with the length of the frame). The angled struts of each cellfunction as a mechanism for rotating the fibers of the skirt in the samedirection of the struts, allowing the skirt to elongate along the lengthof the struts. This allows for greater elongation of the skirt andavoids undesirable deformation of the struts when the prosthetic valveis crimped.

In addition, the spacing between the woven fibers or yarns can beincreased to facilitate elongation of the skirt in the axial direction.For example, for a PET skirt 16 formed from 20-denier yarn, the yarndensity can be about 15% to about 30% less than a conventional PETskirt. In some examples, the yarn spacing of the skirt 16 can be fromabout 155 yarns per inch to about 180 yarns per inch, such about 160yarns per inch, whereas in a conventional PET skirt the yarn spacing canbe from about 217 yarns per inch to about 247 yarns per inch. Theoblique edges 86, 88 promote uniform and even distribution of the fabricmaterial along inner circumference of the frame during crimping so as tominimize bunching of the fabric to facilitate uniform crimping to thesmallest possible diameter. Additionally, cutting diagonal sutures in avertical manner may leave loose fringes along the cut edges. The obliqueedges 86, 88 help minimize this from occurring.

The prosthetic valves disclosed herein can also include an outer skirt(not shown) secured to the outside of the frame. The outer skirt assistsin forming a good seal between the prosthetic valve and the nativeannulus to avoid perivalvular leaks. An outer skirt is further describedin co-pending Application No. U.S. application Ser. No. 13/253,689,filed Oct. 5, 2011, which is incorporated herein by reference.

The prosthetic valves disclosed herein can be implanted via knowntechniques. For example, a prosthetic valve can be implanted in aretrograde approach where the prosthetic valve, mounted in a crimpedstate at the distal end of a delivery apparatus, is introduced into thebody via the femoral artery and advanced through the aortic arch to theheart. A prosthetic valve can also be also be implanted via atransapical approach where the prosthetic valve, mounted in a crimpedstate at the end of a delivery apparatus, is inserted into the heart viaa surgical incision in the chest and the apex of the heart.

FIGS. 9 and 10 show two possible positions for implanting a prostheticheart valve of the present disclosure within the native aortic valve.FIG. 9 shows a first position in which the lobed portions 108 ofprosthetic valve 100 are aligned with the native sinuses in the aorticroot to fit the native anatomy. FIG. 10 shows a second position in whichthe prosthetic valve 100 is rotated 60 degrees from the position shownin FIG. 9. In the position shown in FIG. 10, the commissures 42 of theprosthetic valve are generally aligned with the coronary arteries tomaximize the space between the openings of the coronary arteries and theouter surface of the prosthetic valve.

FIGS. 11-12 show a balloon assembly 200 of a delivery apparatus,according to one embodiment, that can be used to expand a prostheticvalve to an expanded shape in which the commissure supports 18 are bentradially inwardly relative to the sections of the frame extendingbetween the commissure supports. The balloon assembly 200 is mounted tothe distal end of an elongated shaft 206 of the delivery apparatus. Theballoon assembly 200 in the illustrated embodiment includes a centerballoon 202 and a plurality of peripheral balloons 204 a, 204 bsurrounding the center balloon. The proximal ends of all of the balloonscan be fluidly connected to a central inflation lumen extending throughthe shaft 206, which allows an inflation fluid to flow into each of theballoons.

The peripheral balloons include a first set of balloons 204 a and asecond set of relatively shorter balloons 204 b that do not extend theentire length of the balloon assembly. Each of the shorter balloons 204b is positioned between two longer balloons 204 a. The bare frame 12(without leaflets or skirt) is shown in FIGS. 11 and 12 for purposes ofillustration. When the prosthetic valve 10 is crimped and positioned onthe balloon assembly 200 for delivery in a patient, the commissuresupports 18 are aligned with the tapered ends of the shorter balloons204 b. Thus, when the balloons are inflated, the portion of the frame 12below the commissure supports 18 expands to a cylindrical configuration,while the commissure portions 18 do not fully expand and therefore aretitled or bent radially inwardly relative to the struts extendingbetween the commissure portions.

FIG. 13 is a side elevation view of a prosthetic heart valve 300,according to another embodiment. FIG. 14 is a top plan view of theprosthetic valve 300. The illustrated prosthetic valve is adapted to beimplanted in the native aortic annulus, although in other embodiments itcan be adapted to be implanted in the other native annuluses of theheart. The prosthetic valve 300 can have three main components: a stent,or frame, 302, a valvular structure 304, and an inner skirt 306. Theprosthetic valve 300 is configured to be radially compressed to acrimped state for delivery into the body of a patient and radiallyexpandable from the crimped state to an expanded state once positionedat the desired implantation location within the body.

The valvular structure 304 can comprise three leaflets 308, collectivelyforming a leaflet structure, which can be arranged to collapse in atricuspid arrangement, as best shown in FIG. 14. The leaflets 308 can beformed of pericardial tissue (e.g., bovine pericardial tissue),biocompatible synthetic materials, or various other suitable natural orsynthetic materials as known in the art and described in U.S. Pat. No.6,730,118, which is incorporated by reference herein.

As shown in FIG. 13, the frame 302 comprises a plurality oflongitudinally extending, sinusoidal-shaped or undulating struts 310connected to each other at nodes 312 so as to define a plurality of opencells arranged in rows along the longitudinal flow axis of the frame.The frame 302 comprises an inflow end portion 314 that increases indiameter from a diameter D1 at an inflow end of the frame to arelatively larger diameter D2 at a distance spaced from the inflow endof the frame. An intermediate portion 316 of the frame defines a“landing zone” for the frame in that the intermediate portion ispositioned within the native annulus when the prosthetic valve isdeployed. The intermediate portion initially decreases in diameter fromdiameter D2 to a relatively smaller diameter D3 at about a middlesection 318 of the intermediate portion and then increases in diameterto a diameter D4 proximate the outflow end of the frame. The middlesection 318 of the intermediate portion can be a cylindrical shapehaving a relatively constant diameter D3 along the length of the framebetween the section that decreases in diameter from diameter D2 todiameter D3 and the section that increases in diameter from D3 todiameter D4. An outflow portion 320 of the frame decreases in diameterfrom diameter D4 at the outflow end of the intermediate portion to adiameter D5 at an outflow end of the frame. In particular embodiments,D2 is equal to D4, D1 is equal to D3, and D5 is less than D1, D2, D3 andD4.

FIG. 15 shows the frame 302 in a flattened, or unrolled, configuration.As best shown in FIG. 15, the outflow end portion 320 of the framecomprises a plurality of circumferentially spaced, longitudinallyextending commissure attachment portions, or posts, 322 interspacedbetween a plurality of frame retaining arms, or posts, 324. Theretaining arms 324 are used to form a releasable connection between theprosthetic valve 300 and corresponding components at the distal end of adelivery catheter to retain the prosthetic valve at the end of thedelivery catheter until the prosthetic valve is properly positioned atits target deployment location within the body. The retaining arms 324typically are used when the frame is a self-expanding frame since thereis no balloon to retain the prosthetic valve in place during deployment.If the frame is a plastically-expandable frame that is deployed with aballoon or similar expansion device, the retaining arms typically arenot provided. Details of a delivery device that is configured to retaina self-expandable prosthetic valve via retaining arms 324 is disclosedin U.S. Patent Application Publication No. 2010/0049313, which isincorporated herein by reference. In the illustrated embodiment, theframe 302 has six such retaining arms 324, although a greater or fewernumber of retaining arms may be used. Also, the frame 302 in theillustrated embodiment has three commissure attachment portions 322corresponding to the three commissures formed by the leaflets 308. Theframe can have a greater or fewer number of commissure attachmentportions 322 if there are a greater or fewer number of commissuresformed by the leaflets 308.

As shown in FIG. 13, the retaining arms 324 in the illustratedconfiguration extend generally parallel to the flow axis A of theprosthetic valve, or inwardly at a very small angle (e.g., about 1-2degrees) with respect to the flow axis A, while the commissureattachment portions 322 extend inwardly at a much sharper angle withrespect the flow axis A. In particular embodiments, for example, thecommissure attachment portions 322 extend inwardly with respect to theflow axis A at an angle of about 10 degrees to about 60 degrees, andmore particularly, at an angle of about 15 degrees to about 45 degrees.The upper free ends of the commissure attachment portions 322 define theoutflow diameter D5 of the prosthetic valve. The retaining arms 324define a diameter D6, which can be greater than the outflow diameter D5.

The shape of the frame 302 as depicted in FIG. 13 has severaladvantages. The prosthetic valve 300 typically is positioned within thesheath of a delivery apparatus such that the inflow end portion 314 isadjacent the distal opening of the sheath. The tapered inflow endportion 314 can obviate the need for a separate nose cone at the distalend of the delivery apparatus, which typically is used to shield the endof the frame from contacting surrounding tissue during delivery of theprosthetic valve through the patient's vasculature. The tapered inflowend portion 314, which typically is deployed first from the sheathduring retrograde delivery to the native aortic valve, can reduce therisk of trauma to native tissue, such as the aortic annulus and thenative leaflets, as the prosthetic valve is deployed from the sheath.The tapered inflow end portion also reduces the risk of conductionsystem obstruction.

The tapered outflow portion 320 of the frame reduces the risk ofobstructing the coronary ostia when the prosthetic valve is implanted inthe native aortic annulus. When implanted, the outflow portion is spacedinwardly of the aortic root, allowing blood to flow into the coronaryarteries. Moreover, the tapered outflow portion can reduce the risk thatcalcified native leaflets will be pushed against and block the coronaryostia. Also, when deploying, positioning, or retrieving the prostheticvalve and during normal operation of the implanted prosthetic valve, thetapered outflow portion reduces the risk of interaction with thesinotubular junction.

The shape of the intermediate section 316 facilitates positioning of theprosthetic valve by providing a relative large middle section 318 forpositioning within the native annulus. The enlarged inflow and outflowsections 326, 328, respectively, of the intermediate section 316 (at D2and D4) assist in centering the prosthetic valve lengthwise with respectto the native annulus. The enlarged inflow and outflow sections 326, 328also enhance anchoring of the prosthetic valve by engaging the lower andupper portions of the native valve. Thus, the inflow section 326 canengage the ventricular side of the native aortic valve and inhibitimplant migration toward the aorta, while the outflow section 328 canengage the aortic side of the native aortic valve and inhibit implantmigration toward the left ventricle. In this manner, the intermediateportion 316 can provide stable fixation for the prosthetic valve evenfor a non-calcified aortic root. Moreover, contact between the enlargedinflow section 326 and adjacent tissue and between the enlarged outflowsection 328 and adjacent tissue can enhance perivalvular sealing betweenthe skirt 306 and the native annulus.

Another advantage of the frame design is that is facilitatesre-sheathing and/or repositioning of the prosthetic valve. As notedabove, the retaining arms 324 of the frame can be secured to connectiondevices on the distal end of the delivery apparatus when the prostheticvalve is being implanted in the body. Under ideal circumstances, theprosthetic valve is implanted by deploying the prosthetic valve from thesheath of the delivery apparatus at or near the deployment location,adjusting the position of the prosthetic valve (if necessary) andreleasing the connection between the retaining arms 324 and the deliveryapparatus. In some cases, it may be necessary or desirable to fully orpartially re-sheath the prosthetic valve (retract the prosthetic valveback into the sheath) after it is deployed in order to reposition theprosthetic valve or to remove it completely from the body. Because thecommissure attachment portions 322 extend radially inwardly relative tothe retaining arms 324, the distal ends of the commissure attachmentportions 322 can be retained in a compressed state having a compresseddiameter smaller than the inner diameter of the sheath of the deliveryapparatus. Thus, even if the prosthetic valve is fully deployed from thedelivery sheath, the commissure attachment portions 322 can be retractedback into the sheath, followed by the remaining portion of theprosthetic valve for repositioning the prosthetic valve or withdrawingit from the body.

FIG. 16 is a top plan view of the prosthetic valve 300 with the skirt306 removed for purposes of illustration. FIG. 16 also shows theleaflets 308 in an open position under systolic pressure, allowing bloodto flow through the prosthetic valve. As can be seen, the cantileveredand angled commissure attachment portions 322 support respectivecommissures 330 of the valvular structure inwardly toward the centralflow axis A and away from adjacent portions of the frame 302 to avoidcontact between the moveable portions of the leaflets and the frame. Theangled commissure attachment portions 322 also reduce the distancebetween the commissures, enabling a more efficient leaflet design, asfurther described below. As noted above, the angle of the commissureattachment portions 322 can be varied depending on the particularapplication. FIG. 17 shows an embodiment where the commissure attachmentportions 322 extend inwardly at about a 60-degree angle relative to theretaining arms 324. FIG. 18 shows an embodiment where the commissureattachment portions 322 extend inwardly at about a 15-degree anglerelative to the retaining arms 324.

FIG. 19 shows a leaflet 308 of the valvular structure 304. The leaflet308 in the illustrated embodiment comprises a substantially V-shaped orscalloped lower edge 332 extending between the lower edges of tabs 334and a substantially V-shaped or scalloped upper edge 336 extendingbetween the upper edges of the tabs 334. By reducing the distancebetween the commissures 330, the width W of the leaflet 308 (measuredbetween opposing side edges at any location along the height H of theleaflet) can be minimized and the upper edge 336 can have a relativelypronounced concavity, which reduces the overall size of the leafletcompared to a known leaflet 150 (FIG. 6) for the same size prostheticvalve. The smaller, more efficient leaflet design occupies much lessspace inside the crimped prosthetic valve and therefore allows theprosthetic valve to be crimped to a smaller diameter for delivery.

Because the commissure attachment portions 322 are cantilevered relativeto the frame, they can deflect slightly during operation of theprosthetic valve, which improves valve operation and durability. Inparticular, when the leaflets 308 close under diastolic pressure, thecommissure attachment portions 322 can deflect inwardly to relievestress and strain on the leaflets (especially the commissure attachmentpoints of the leaflet tabs 334), which improves long term durability ofthe leaflets. Also, when the leaflets open under systolic pressure (asdepicted in FIG. 16), the upper edges 336 of the leaflets are retainedat a position spaced from the inner surface of the frame to preventabrasion and increase leaflet durability. Providing an enlarged diameterD4 (FIG. 13) within the outflow portion 320 of the frame also assists increating a gap between the inner surface of the frame and the leafletswhen the leaflets are in the open position.

The cantilevered commissure attachment portions 322 can also help avoid“pinwheeling” of the leaflets. “Pinwheeling” is a phenomenoncharacterized by twisting of the upper edges of the leaflets when theleaflets close under diastolic pressure. The twisting motion results inincreased flexion and stress on the leaflets, which can adversely effectthe durability of the leaflets. The flexible commissure attachmentportions 322 can absorb some of the closing forces on the leaflets andallow the leaflets to close more gently under diastolic pressure,thereby preventing or at least minimizing the pinwheeling effect.

The concave upper edges 336 of the leaflets and the cantileveredcommissure attachment portions 322 can also help avoid “reverse bending”of the leaflets. “Reverse bending” of leaflets refers to irregular foldsor bends that can occur when the leaflets open under systolic pressure.The stresses generated on the leaflet tissue by such bending or foldingof the leaflets can lead to fatigue failure of the leaflet. When theleaflets 308 open under systolic pressure, the commissure attachmentportions 322 are deflect slightly outwardly away from the flow axis A,taking up or reducing slack along the upper edges 336 of the leaflets.This inhibits the formation of irregular folds or bends in the leaflets,allowing the leaflets mimic the shape of the native aortic leaflets inthe open position. The concave upper edges of the leaflets also reducesthe amount of slack between the commissures to further ensure theleaflets can be achieve a more natural shape without irregular folds orbends when opened under systolic pressure.

FIG. 15A is an enlarged view of a commissure attachment portion 322. Thecommissure attachment portion 322 comprises at least two cantileveredstruts that are configured to provide a clamping or pinching forceagainst a pair of leaflet tabs 334 to assist in securing the leaflettabs to the frame. In the illustrated configuration, each attachmentportion 322 comprises two cantilevered inner struts 338 and twocantilevered outer struts 340 extending from a common base 342. The twoinner struts 338 are spaced apart from each other to define aleaflet-receiving gap therebetween. Similarly, each outer strut 340 isspaced apart from a corresponding adjacent inner strut 338 to define arespective leaflet-receiving gap therebetween. The inner and outerstruts 338, 340 are used to secure the commissures 330 of the leaflets.Each outer strut 340 can be formed with a small recess or notch 344 thatcan be used to retain a suture that extends around the attachmentportion 322, as further described below.

Referring now to FIGS. 20-25, a method for securing the commissures 330to the commissure attachment portion 322 will now be described. Eachcommissure attachment portion 322 supports a pair of adjacent tabportions 334 of two leaflets 308 on the inner and outer struts 338, 340.As best shown in FIG. 23, a pair of tab portions 334 a and 334 b extendthrough the gap between the inner struts 338. On the radial outer sideof the commissure attachment portion, the tab portions 334 are foldedaway from each other, forming a first fold 346 a and a second fold 346b. The first fold 346 a extends through a respective gap between aninner strut 338 and an adjacent outer strut 340. The second fold 346 bextends through a respective gap between the inner strut 338 and theadjacent outer strut 340. Tab portion 334 a can then be folded again toform a fold 348 a that lies against the outside of fold 346 a. Likewise,tab portion 334 b can be folded again to form a fold 348 b that liesagainst the outside of fold 346 b. Fold 348 a can be secured to fold 346a by a suture 350 a that extends along the length of the folds.Likewise, fold 348 b can be secured to fold 346 b by a suture 350 b thatextends along the length of the folds.

Each pair of the tab portions 334 can be reinforced with a reinforcementportion 352, which can be cut or otherwise formed from a sheet ofstrong, flexible material, such as PET. The reinforcement portion 352reinforces the connection of the leaflet tab portions to the frame andprotects the portions of the leaflets on the outside of the frame fromcontacting the delivery sheath. The reinforcement portions 352 can bethree separate pieces of material mounted to the commissure attachmentportions 322. Alternatively, the reinforcement portions 352 can beintegral upper extensions of the skirt 306 (i.e., the skirt 306 and thereinforcement portions 352 can be a single piece of material).

FIG. 20 shows a commissure 330 before a reinforcement portion 352 isplaced on and secured to the attachment portion 322. FIG. 21 shows areinforcement portion 352 in an unfolded configuration prior to beingplaced on and secured to an attachment portion 322. The reinforcementportion 352 can be folded partially around a pair of tab portions 334 toform a rear portion 354 (FIGS. 24-25) that extends along the radialoutside surface of the commissure attachment portion 322. Extending fromthe longitudinal edges of the rear portion 354 are side flaps 356 a, 356b. As best shown in FIG. 23, side flap 356 a extends between leafletfold 346 a and an adjacent outer strut 340 and side flap 356 b extendsbetween leaflet fold 346 b and an adjacent outer strut 340. As bestshown in FIG. 22, a top flap 358 extends from the upper edge of the rearportion 354 and covers the top of the commissure attachment portion 322.A front flap 360 extends downwardly from the front edge of the top flapand covers the portion of the commissure attachment portion 322 abovethe leaflets. Two upper side flaps 362 extend downwardly from the upperside edges of the top flap 358 and cover the opposite sides of thecommissure attachment portion 322 above the leaflets. As best shown inFIG. 24, each of the side flaps 362 can be a double layer comprising aninner fold and an outer fold.

The leaflet tab portions 334 and the reinforcement portion 352 can betightly secured to the inner and outer struts 338, 340 by a suture loop364 (FIG. 23) that is tightened around the upper end portions of thestruts 338, 340. Because the struts 338, 340 are cantilevered themselvesand unattached to each other at their upper ends, tightening the sutureloop 364 draws the struts 338, 340 inwardly toward the longitudinalcenterline of the commissure attachment portions 322 (the lineequidistant from the inner struts 338), thereby clamping the folds ofthe leaflets and the reinforcement portion between the struts 338, 340.The suture loop 364 can be located within the notches 344 (FIG. 15A) ofthe outer struts 340, which prevent the loop 364 from sliding along thelength of the struts. Another suture loop 366 (FIGS. 24 and 25) can betightened around the lower end of the commissure attachment portion 322and lower end portion of the reinforcement portion 352.

The lower edge 332 of each leaflet 308 can be secured to the skirt 306along a suture line 368 (FIG. 13). The lowermost sections of the loweredges 332 of the leaflets (indicated by suture line 368) desirably arealigned with the inflow edge of the frame 302. In this manner, theleaflets 308 extend the entire length or substantially the entire lengthof the frame from the inlet end to the outlet end of the frame. Theskirt 306 can be secured directly to the frame 302 with sutures (notshown), in the same manner that skirt 16 (FIG. 1) is secured to theframe 12 with sutures 60.

The process suturing leaflet commissures to a frame is a time-consumingand tedious process. The struts 338, 340 of the commissure attachmentportions are advantageous in that they provide a robust attachment forthe leaflet tab portions 334 while significantly minimizing the extentof suturing required to secure the leaflet commissures to the framecompared to known techniques. In particular embodiments, for example,only two suture loops 364, 366 are used to secure a reinforcementportion 352 to a commissure attachment portion 322 and to a pair ofleaflet tab portions 334, and other than sutures 350 a, 350 b, nofurther stitching is required to secure together multiple folds of theleaflet to each other or to the folds of the reinforcement portion 352.

Another important advantage provided by the commissure attachmentportions is that they minimize the amount of leaflet material positionedon the outside of the frame. This reduces friction between the outsideof the prosthetic valve and the deliver sheath, such as when theprosthetic valve is deployed from the sheath. Moreover, if theprosthetic valve is retracted back into the sheath after its initialdeployment, the prosthetic valve can slide more easily back into thesheath while minimizing the risk of damage to the leaflet material onthe outside of the frame that may occur from contact with the distal endof the sheath.

FIG. 26 shows another embodiment of a frame 400 that can be used in theprosthetic valve 300. Frame 400 is similar to frame 302 (FIG. 15),except for the number of cells bridging the intermediate portion 316 andthe outflow portion 320. Referring to FIG. 15, except for the uppermostrow of cells formed by the retaining arms 324, each row 370 of cells ofthe frame includes twelve cells 372. Referring to FIG. 26, the uppermostrow 402 of cells bridging the intermediate portion 316 and the outflowportion 320 includes six cells 404, which reduces the amount of metal inthat portion of the frame. The uppermost row 402 of cells circumscribesthe widest portion of the leaflets (except for the tab portions 334) andtherefore corresponds to the volume occupied by the bulk of the leafletswhen the prosthetic valve is radially crimped. Therefore, the removal ofmetal from the frame, and in particular from the portion of the framecircumscribing the widest portion of the leaflets, allows for a smallercrimped diameter for the prosthetic valve.

FIG. 27 illustrates an embodiment of a prosthetic valve 500, which isdescribed in detail in U.S. Pat. No. 7,993,394, which is incorporatedherein by reference. The prosthetic valve 500 can have three maincomponents: a stent, or frame, 502, a valvular structure 504, and aninner skirt 506. The prosthetic valve 500 is configured to be radiallycompressed to a crimped state for delivery into the body of a patientand radially expandable from the crimped state to an expanded state oncepositioned at the desired implantation location within the body. Thevalvular structure 504 can comprise three leaflets 508, collectivelyforming a leaflet structure, which can be arranged to collapse in atricuspid arrangement, as shown.

FIG. 28 is an enlarged view of a section of the prosthetic valve 500showing the connection of a commissure 510 of two adjacent leaflets 508to the frame. As shown, the commissure 510 is formed by securing a pairof leaflet tab portions 512 to each other and to a commissure attachmentpost 514 of the frame 502 with sutures 520. The lower edges of theleaflets 508 can be sutured to the skirt 506 along a suture line 516,and the skirt 506 can be secured to the frame 502 with sutures 518.

FIG. 29 shows a stent, or frame, 600 according to another embodimentthat can be used in the prosthetic valve 500 of FIGS. 27 and 28. Inparticular embodiments, the frame 600 is a plastically-expandable frame(i.e., is expanded with a balloon or equivalent mechanism) and isconfigured to undergo post-deployment shaping after being deployed in apatient's body. In particular, the frame 600 in the illustratedconfiguration is configured to be deployed into a generally cylindricalconfiguration using a conventional cylindrical balloon, and afterdeflating and removing the balloon, the commissure attachment portionscan bend inwardly to support the commissures of the leaflets atlocations closer to the central flow axis of the prosthetic valve. Inparticular embodiments, a prosthetic valve can comprise the frame 600and the leaflet structure 304 comprising leaflets 308 of the prostheticvalve 300.

FIG. 29 shows the frame 600 in a radially expanded state after beingexpanded by an inflatable balloon of a balloon catheter. The balloon canbe a conventional balloon that assumes a generally cylindrical shapewhen inflated. Hence, as depicted in FIG. 29, the frame 600 can assume agenerally cylindrical shape when expanded by the balloon. The frame 600in the illustrated configuration comprises a plurality of commissureattachment posts, or struts, 602 (three in the illustrated embodiment),a first row of struts 604 at the inflow end of the frame, and a secondrow of struts 606 and a third row of struts 608 at the outflow end ofthe frame. A plurality of longitudinal struts 610 extend between theapices of the first row of struts 604 and nodes 612 adjoining adjacentcells formed by struts 606 and 608.

The frame 600 is configured to permit inward titling or displacement ofthe upper portions 614 of the commissure attachment posts 602 when theyare first subjected to a closing force of the leaflets under diastolicpressure and then remain in the tilted position. To such ends, struts606 a and 608 a that are connected directly to the commissure attachmentposts 602 can be weakened relative to the other struts by reducing orthinning the cross-sectional profile of the struts 606 a, 608 a, such asby reducing the thickness and/or width of the struts 606 a, 608 a, andby providing one or more curves or bends in the struts 606 a, 608 a. Thecurves or bends in the struts 606 a, 608 a provide slack in those strutsto permit the commissure attachment posts 602 to flex inwardly relativeto longitudinal struts 610.

When the prosthetic valve is first deployed within the native aorticvalve (or another native heart valve) by inflating a balloon, the frame600 is expanded to the expanded shape shown in FIG. 29. Upon deflationand removal of the balloon, diastolic pressure causes the leaflets(e.g., leaflets 508) to close, and the closing force of the leafletsdraws the upper portions 614 of the commissure attachment posts 602 tobend or tilt inwardly to the positions shown in FIGS. 30 and 31. As theposts 602 are drawn inwardly, the struts 606 a, 608 a are straightenedand limit further bending of the posts 602. The struts 606 a, 608 a intheir straightened or nearly straightened configuration exhibitsufficient rigidity to retain the posts 602 in their titled positionunder systolic pressure. Thus, after the initial prosthetic valveclosing, the posts 602 remain their titled position supporting thecommissures (e.g., commissures 510) closer to the longitudinal flow axisof the prosthetic valve. Accordingly, a plastically-expandableprosthetic valve incorporating the frame 600 can achieve an overallshape similar to that shown in FIGS. 11 and 12 without a speciallyshaped balloon assembly. The inwardly canted posts 602 support themoveable portions of the leaflets away from the inner surface of theframe 600 when the leaflets are in the open position, thereby protectingthe leaflets against abrasion caused by contact between the leaflets andthe frame, as previously discussed.

If desired, the struts 604 a of the first row that are connecteddirectly to the posts 602 can have a configuration similar to posts 606a, 608 a. Weakening the struts 604 a connected to the lower ends ofposts 602 can facilitate displacement of the posts 602 by allowing forslight outward deflection of the lower ends of the posts 602. Inaddition, the posts 602 can be weakened at one or more selectedlocations to facilitate displacement of the posts. As shown in FIGS. 32and 33, for example, each post 602 can have a slit, or recessed portion,616 formed in the inner surface of the post at a location just above thefirst row of struts 604. The recessed portions 616 weakens the posts 602and function as a pivot for the posts, allowing the posts to more easilybend at the recessed portions 616 when subjected to the force of theinitial closing of the leaflets. In addition to or in lieu of therecessed portions 616, the posts 602 can be weakened by reducing thewidth and/or the thickness of the posts at selected locations tofacilitate displacement of the posts.

A modification of the frame 600 is shown in FIG. 34. In this embodimentof the frame 600, tether or wires 618 can be used to limit the extent ofinward displacement of the upper end portions of the posts. For example,each post 602 can be connected to a pair of wires 618, each having oneend secured to an apex 620 of the third row of struts and another endsecured to the upper end portion 614 of the post 602. When the frame isinitially expanded and before subjected to the closing force of theleaflets, there is sufficient slack in the wires 618 to allow the posts602 to bend inwardly. The length of the wires 618 is selected to allowthe posts 602 to bend or tilt inwardly a limited amount when subjectedto the force of the initial closing of the leaflets. Upon initialclosing of the leaflets, the wires 618 are pulled taught and limit theextent to which the upper end portions of the posts 602 can be pulledinwardly by the force of the leaflets.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim all that comes within the scope and spirit of these claims andtheir equivalents.

1. A prosthetic heart valve comprising: a radially-collapsible annularframe having an inflow end, and outflow end, an inflow end row of cellsadjacent the inflow end, and an outflow end row of cells adjacent theoutflow end, wherein the frame comprises a plurality of struts arrangedto form the cells of the inflow end row of cells and the outflow end rowof cells, and selected struts of the outflow end row of cells definecommissure portions of the frame; and a valve structure positionedwithin the frame and secured to the commissure portions, the valvestructure configured to open during systole and close during diastolewhen the prosthetic heart valve is implanted in a patient; wherein cellsof the outflow end row of cells are larger than cells of the inflow endrow of cells; and wherein the commissure portions of the frame flexradially inwardly when the valve structure closes during diastole. 2.The prosthetic heart valve of claim 1, wherein the cells of the outflowend row of cells have a greater axial length than the cells of theinflow end row of cells.
 3. The prosthetic heart valve of claim 1,wherein the outflow end of the frame includes axial projections thatextend axially from the outflow end row of cells and are configured toform a release connection with a delivery apparatus.
 4. The prostheticheart valve of claim 1, wherein the outflow end of the frame reduces indiameter when the commissure portions of the frame flex radiallyinwardly.
 5. The prosthetic heart valve of claim 1, wherein thecommissure portions move closer together when the commissure portionsflex radially inwardly.
 6. The prosthetic heart valve of claim 1,wherein the commissure portions comprise three commissure portions andthe valve structure comprises three leaflets, each leaflet being securedto two of the three commissure portions.
 7. The prosthetic heart valveof claim 1, wherein the cells of the inflow row of cells are diamondshaped.
 8. The prosthetic heart valve of claim 1, wherein the cells ofthe outflow row of cells are diamond shaped.
 9. The prosthetic heartvalve of claim 1, wherein the frame comprises shape-memory material. 10.The prosthetic heart valve of claim 1, further comprising an annularinner skirt positioned inside the frame adjacent the inflow end of theframe.
 11. A prosthetic heart valve comprising: a radially-collapsibleannular frame having an inflow end, and outflow end, a first row ofcells adjacent the inflow end, and a second row of cells adjacent theoutflow end; and a leaflet assembly comprising a plurality of leafletsand positioned within the frame, wherein the leaflet assembly has aplurality of commissures secured to commissure portions of the frame,wherein the leaflets are configured to open during systole and closeduring diastole when the prosthetic heart valve is implanted in apatient; wherein cells of the second row of cells are larger than cellsof the first row of cells; and wherein the commissure portions of theframe flex radially inwardly when the valve structure closes duringdiastole.
 12. The prosthetic heart valve of claim 11, wherein the framecomprises a plurality of struts arranged to form the cells of the firstand second rows of cells, and the commissure portions of the frame areselected struts of the second row of cells.
 13. The prosthetic heartvalve of claim 12, wherein the cells of the second row are diamondshaped.
 14. The prosthetic heart valve of claim 12, wherein thecommissure portions of the frame are positioned between axial ends ofthe second row of cells.
 15. The prosthetic heart valve of claim 11,wherein the cells of the second row of cells have a greater axial lengththan the cells of the first row of cells.
 16. The prosthetic heart valveof claim 11, wherein the outflow end of the frame includes axialprojections that extend axially from the second row of cells and areconfigured to form a release connection with a delivery apparatus. 17.The prosthetic heart valve of claim 11, wherein the outflow end of theframe reduces in diameter when the commissure portions of the frame flexradially inwardly.
 18. The prosthetic heart valve of claim 11, whereinthe commissure portions move closer together when the commissureportions flex radially inwardly.
 19. The prosthetic heart valve of claim11, further comprising an annular inner skirt positioned inside theframe adjacent the inflow end of the frame, wherein the inner skirtcomprises a fabric material and has an undulating outflow edge.
 20. Theprosthetic heart valve of claim 11, wherein the frame comprises Nitinoland is self-expanding.